charlie replied:

GQ's sit a bit lower than 80 series as standard for a couple of reasons. The body of the vehicle is not as tall for starters and the way the springs are mounted are slightly lower. I don't think you will find much if any difference in articulation between the two in original form. If you are looking for really good under body clearance from either of these a couple of inches lift will do the trick.

Charlie

Nav 80 replied:

Had a GQ myself a few years back, I bought it new and had to replace the coil springs in the rear at about 20,000 K they just saged and stayed there. I belive it is a coman problem with them however they are not too expensive to replace.
Lovell do a replacement set for around $500-600 if I recall and are a very good, fixed mine a treat.
If you are looking at a diesel over 300,000K be carefull and have a diesel mechanic check it out for you before you buy as they are very expensive to rebuild. A worn out diesel can still start and run and sound OK but in fact be on its last legs,if its breathing through the oil cap I would give it a miss. One simple check you can do is take off the oil filler cap, stick your finger in under the rocker cover and feel for sludge. If it is caked with black sludge its a fair indication of worn rings causing blow by, then stay clear of it,I am a diesel mechanic so I know what I am talking about.